The iPhone app was founded by a team of doctors from Harvard Medical School and uses artificial intelligence to simulate a conversation with a doctor. By asking a series of questions and ruling out possibilities as it goes, Buoy says it provides a more accurate diagnosis than just typing a series of symptoms into Google. Most importantly, Buoy will never tell you you have cancer.

CEO Andrew Le has been working on the app since 2014 and it launched in March. He told Boston Magazine that in a test of 500 patients in the waiting room of a hospital, the app provided the same diagnosis as a real doctor 90% of the time.

The app is free and works much like a text message chat between two people. Here's how to use it.

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Once you create an account on Buoy, you'll be able to start a "chat." It'll start by asking whether you're using the app for yourself or to look up someone else's symptoms. When you begin entering more information, the amount of options will narrow, but the app has more than 1,700 possible illnesses in its system.

Buoy

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Just by telling Buoy I'm female, the app was able to eliminate 18 possible conditions. Telling the app my age eliminated even more.

Buoy

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Next, I started telling Buoy what was wrong physically. I get tension headaches a few times a month that usually last for several days, so I was curious to see if Buoy could figure that out just from hearing my symptoms.

Buoy

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I started by telling Buoy I had a headache. The app immediately followed up with several questions, like how long it's lasted and the severity of the pain.

Buoy

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I added one more symptom — feeling foggy-headed — then Buoy asked me about my lifestyle and any other unusual feelings or symptoms, just like a regular doctor would.

Buoy

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Buoy will also give you groups of responses to choose from when entering your symptoms, which can make it easier to describe them. I didn't realize how stiff my neck was, for example, until I saw it as an option. The app will also show you at the top of the screen the progress it's making in narrowing things down, which is cool to see.

Buoy

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After about 20 questions, Buoy will give you a few options that might explain why you're feeling the way you are. In my case, the app had considered 123 possible illnesses and 9 possible suspects, and decided on 3 likely matches. Sure enough, tension headache was one of them.

Buoy

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Buoy also provides care options, but it typically suggests to go see a doctor. The app makes it clear that it's not diagnosing you, but giving you more accurate estimates of what might be making you feel unwell. Speaking with a human doctor is still your best bet, but Buoy's AI capabilities do a good job in the meantime.

Buoy

Buoy is only available for iOS at the moment. It's free to download (and use) from the App Store.